#include <stdio.h>
int max(int, int);
int main(void) {
int a, b, c, d;
scanf("%d %d %d %d", &a
, &b
, &c
, &d
);
printf("%d",max
(max
(a
,b
),max
(c
,d
))); return 0;
}
int max(int x, int y) {
return (x > y) ? x : y;
}
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